Advancing Carriers Mobility in MnSb2Te4 Thermoelectrics via Tailored Textures and Vacancy Modification

Abstract

Enhancing carrier mobility plays a crucial role in significantly improving thermoelectric performance. However, due to the lack of a systematic strategy, achieving high mobility remains an elusive goal for most compounds. In this study, the hot-forging method is applied to polycrystalline MnSb₂Te₄, achieving a remarkable 300% improvement in carrier mobility. Through electron backscattering diffraction microstructural analysis, it is demonstrated how optimizing textures can accelerate carrier movement in MnSb₂Te₄ bulk materials. Moreover, theoretical calculations, combined with experimental positron annihilation spectroscopy, reveal that Te vacancies help counteract intrinsic cation defects, leading to a simultaneous increase in carrier mobility. As a result, the hot-forged MnSb₂Te₄ specimen, with a diameter of 15 mm, reaches a record-high maximum figure of merit (ZT) value of 1.3 at 773 K and an impressive average ZT of 0.7 between 323 and 773 K. The experimental output efficiency of 4.6%, observed at 773 K on the MnSb₂Te₄-based single-leg module, further confirms that the improved transport properties are due to the enhanced carrier mobility. This comprehensive study offers valuable insights into mobility enhancement in MnSb₂Te₄ and provides a promising direction for exploring similar improvements in other thermoelectric materials.